(a) Field of the Invention
This invention relates to yellow-developing couplers for use in diazo copying materials.
(b) Description of the Prior Art
General diazo copying materials are classified into the one-component type (unitary) copying material containing a diazo compound in the photosensitive layer thereof and the two-component type (binary) copying material containing both a diazo compound and a coupler in the photosensitive layer thereof. As is well known, in the case of the former copying material, it is exposed to light after superposing an original thereon and is thereafter developed with an alkaline liquid developer containing a coupler, and in the case of the latter copying material, it is exposed to light in the same fashion and is thereafter developed with an alkaline liquid developer not containing a coupler.
In the prior art, in the case where such a binary diazo copying material as mentioned above is employed as a secondary original, application of a coupler capable of producing an ultraviolet-interceptive orange-yellow azo dye is prevalent. As coupler of this type, there is generally employed acetoamide derivatives, acetoacetoanilide or acetoacetonaphthalide. Besides, when this yellow-developing coupler is used jointly with a blue-developing couplers (a coupler which can produce a blue dye upon reacting with a diazo compound), there can be formed a black dye. As blue-developing coupler of this type, .beta.-naphthol derivatives are generally employed. However, orange-yellow azo dyes obtained from acetoamide derivatives, etc., as combined with a diazo compound are generally defective in that they are inferior in light fastness, an image formed thereof would disappear when let alone in the light, or, in the case of a black dye image formed thereof, it would cause color-shift.